SEARCH · PubMed Health

Results for “feature stability”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources

PubMed1975

Severe hypertension. Treatment with minoxidil.

Seventeen patients who were partially or totally refractory to maximal doses of conventional antihypertensive agents were treated with minoxidil. Three patients were receiving long-term maintenance dialysis. Propranolol and diuretics were given to prevent reflex tachycardia and fluid retention. Initial control of blood pressure was excellent in 16 patient. In one patient, diastolic blood pressure remained unchanged (120 mm Hg) despite 60 mg of minoxidil and volume depletion. In three other patients, secondary resistance developed, and the addition of guanethidine was necessary. The main side-effects were fluid retention (in eight) and hypertrichosis (in ten), accompanied in some by a peculiar coarsening of the facial features. Renal function stabilized or improved in most, and urine output increased in the three hemodialysis patients. We conclude that minoxidil is a valuable drug in severe hypertension.

Adult↗

PubMed1992

Micro-architecture and composition of artery walls: relationship to location, diameter and the distribution of mechanical stress.

PURPOSE: We reviewed the structural basis of the mechanical properties of the arterial wall, in order to establish a coherent micro-anatomical basis for the differences in compliance among different arteries and a framework for assessing changes in the mechanical properties of specific individual arteries in relation to changing physical stresses. DATA IDENTIFICATION: The data and concepts presented here were derived from both earlier and ongoing work. Features that assure stability and integrity in relation to blood flow (wall shear stress) and pressure (mural tensile stress) were examined. Particular attention was paid to the morphogenetic and biosynthetic means by which arteries adapt to normal or abnormal modifications of these forces, particularly in relation to growth, location in the arterial tree and geometric configuration. RESULTS AND CONCLUSIONS: Thickness, composition and architecture of the artery wall, including thickness and composition of the intima, are normally determined by the stresses imposed by pressure and flow. Vessel radius is closely associated with flow, so that a normal baseline level of mean shear stress of about 15 dyn/cm2 is maintained or restored. Wall thickness and composition are determined by wall tension in relation to pressure and radius. Baseline levels of tensile stress differ with location but appear to be similar for homologous vessels. Changes in flow that modify the radius also modify wall tension. Changes in wall thickness and composition are likely to cause changes in compliance, due to altered flow and/or pressure patterns; these changes in compliance may be adaptive rather than destructive. Changes in the compliance of specific arteries over time may be used to evaluate the progression and severity of the conditions underlying these changes.

Animals↗

PubMed2004

CDX-2 expression is reduced in colorectal carcinomas with solid growth pattern and proximal location, but is largely independent of MSI status.

The homeobox genes are transcription factors that control the development of tissues and organs. In the colon one of such genes is CDX-2. In colorectal carcinomas, the CDX-2 expression is reduced. The aim of the present study was to investigate the presence of CDX-2 in colorectal carcinomas and to relate it to the histological features and microsatellite stability status. The material consisted of 20 carcinomas without microsatellite instability, 19 cases with low microsatellite instability and 19 cases with high microsatellite instability. CDX-2 expression was investigated using immunohistochemistry with CDX2-88 monoclonal antibody and assessed semiquantitatively. In 10 cases no expression of CDX-2 was observed, while in 6 the protein was present in less than 25% of tumor cells. It was noted that reduced expression of CDX-2 was more frequent in carcinomas situated proximally to the splenic flexure (p < 0.015) and in tumors with solid growth pattern (p < 0.03). On the other hand, no significant differences were encountered between groups differing in microsatellite stability. The results suggest that the major factors that determine the presence of CDX-2 in colorectal carcinomas at the protein product level may include cancer location and the solid phenotype of the tumor.

Adenocarcinoma↗

PubMed2005

Active-fixation, steroid-eluting ventricular leads: the medium-term results in children.

OBJECTIVE: Low threshold characteristics and mechanical stability are important features of an ideal pacing lead, especially for children. We report our experience and medium-term results with a steroid-eluting, active-fixation ventricular lead in children. METHODS: Telectronics Accufix II DEC model 033-212 ventricular leads were implanted in 21 patients. Eighteen patients (11 male / 7 female; 10.6+/-4.0 years), who were followed for a mean period of 6.47 +/-1.13 years, were included in the study. RESULTS: Pacemaker mode was DDDR in three patients, and VVIR in the remaining 15 patients. Mean threshold value was 0.5 volts at implant, which increased to 0.7 volts in the first month (p>0.05). It remained stable (0.62-0.78 V) until 5.5 years (p>0.05), increased significantly at 5.5 years (0.99+/-0.63 V at 5.5 years, p<0.05) and remained significantly high after this time (p<0.05). Pacing lead impedance did not differ significantly throughout the study (p>0.05). Thirteen pulse generators reached end-of-life at > or =4 years. In all the patients whose generators were replaced (11 patients), the leads were kept in place. CONCLUSION: Steroid-eluting active-fixation ventricular leads have long service lives and low chronic stimulation threshold values, allowing lower outputs. These features may have advantages in pacing therapy of children.

Adolescent↗

PubMed1984

[Continuous alfentanil infusion in surgical interventions of intermediate and long duration].

Alfentanil, a new short-acting narcotic analgesic, was studied as a continuous infusion for surgical procedures of medium and long duration in 80 patients. Anaesthesia was induced with thiopentone immediately followed by 1 mg of alfentanil to attenuate the stress response to intubation. Alfentanil 100 micrograms/kg was then slowly given as a loading dose before surgery started and anaesthesia maintained by a continuous infusion at a rate of 0.5-1 micrograms/kg/min. Patients were ventilated with a 66% nitrous oxide in oxygen. The course of anaesthesia was good in 76 of the patients, while 27 needed small increments of alfentanil on top of the infusion. Cardiovascular stability was a feature in almost all patients. Recovery was extremely rapid and without complications. Naloxone to reverse respiratory depression was only used twice.

Adolescent↗

PubMed1984

Alfentanil analgesia for surgical procedures of medium and long duration.

The clinical potential of alfentanil, a short acting narcotic analgesic as a supplement to only nitrous oxide/oxygen was evaluated in 141 patients having surgery of medium and long duration. Following induction of anesthesia with thiopentone alfentanil 1 mg was injected just prior to intubation. Anesthesia was maintained with a mixture of nitrous oxide/oxygen, (2:1) with analgesia achieved by a loading dose of alfentanil 0.1 mg/kg slowly given over 5 to 10 minute period prior to surgery. Additional increments (10-15 micrograms/kg) were given when the expected length of the operation was more than 30 minutes. The course of anesthesia was rated good in 96.4% of the patients. Cardiovascular stability was a feature in almost all patients. Stress responses due to severe surgical stimuli were almost immediately abolished by the administration of small increments of alfentanil (0.5-1 mg). Recovery was extremely rapid and without side-effects. Reversal of respiratory depression was rarely needed.

Adolescent↗

PubMed1984

[Isolation and characteristics of Chinese hamster cells resistant to colchicine].

Several ClchR clones of CHO-K1 have been isolated by a single- and multistep selection. They are distinct from each other both in the level of colchicine resistance and in the phenotypic stability of this feature. Fluctuation tests showed that the generation of drug resistant variants in the wild type population was random and did not depend on the action of selective agent. The rate of spontaneous occurrence of these variants was approximatley 1.79 x 10(-6) per cell per generation. Treatment with MNNG enhanced the frequency of ClchR variants by 100 fold. Cytotoxic effect of Clch on resistant cells has been potentiated by non-ionic detergent Tween 80. All the stable resistant clones appeared to be cross resistant to unrelated drugs such as actinomycin D, ethydium bromide and aminopterine . These two observations allow to suggest the alteration of membrane permeability as a mechanism of resistance to Clch . Genetical mechanisms of Clch -resistance of cells are discussed.

Aminopterin↗

PubMed1978

[Clinical and statistical study of the use of alpha-MPG in the treatment of viral hepatitis].

Several workers have already employed alpha-MPG in the management of acute vital hepatitis as a sulphydrylating agent to combat viral poisoning of the liver cells. Its distinct features include the stability of its molecule, its biochemical attributes in the course of time, and its virtually similar oral and injectable LD(50) (2100 MG/KG). High doses, well above those possible with earlier sulphydrylating agents, were used in a trial of alpha-MPG against UDPG. The new drug proved more active and led to a particularly significant fall in SGPT. Subjective and biohumoral parameters returned to normal more quickly, though the differences were not significant. Tolerance was good. Subjective over-reaction with a slight rise in temperature and allergic exanthema was noted in 3 cases. This promptly regressed when the treatment was suspended.

Acute Disease↗

PubMed1994

[Results of various reconstructive procedures in defects of the fronto-facial area].

Small calvarial defects may be recontoured by Gore-Tex membranes or by micro burr hole covering plates in combination with bone dust. In extended defects the best primary and secondary results are obtained with splitted calvarium grafts due to their stabilizing and esthetic features. Micromeshes prevent contour disturbances in the contact zone of the transplants.

Bone Transplantation↗

PubMed1996

Studies on the stability of HSV-1 temperature sensitive 28 degrees C clone.

The temperature mutants of herpes simplex virus type 1 has been received. The following properties on different levels of passages were investigated: stability of virulence, virus infection titer and immunogenicity. The virulence stability was expressed by percent of survivors and mean survival time in infected mice (CFW/Pzh and BALB/cPzh strains). Virus infection titer's stability was measured after prolonged exposure of temperature sensitive mutant (ts 28 degrees C) to critical temperatures (+4 degrees C and from +20 degrees C to +23 degrees C). Stability of immunogenic potency of ts 28 degrees C was evaluated in mice immunized with the virus on different level of passages and after that they were challenged with highly pathogenic temperature resistant clone (tr 39 degrees C). The performed experiments proved the stability of investigated features.

Animals↗

PubMedDate not supplied

The quality of self-concept in old age.

Self-concept in old age was investigated. The goal of the work was to reveal the contents of self-concept, that is, what is included in the sphere of self-assessment, and also to analyze the traditional parameters of self-assessment: its height, stability, adequacy. Specific features of self-concept in old age were found. They concern the contents of self-concept and are characterized by retrospective direction of self-analysis. Total lowering of the level of self-assessment and modification of its structure including real, ideal, attainable positions were found. As compared with previous periods of the life-cycle, self-concept becomes less stable and adequate. Besides the general peculiarities, old people's self-concept is characterized by wide individual variations and sex differences.

Adaptation, Psychological↗

PubMed1996

[Development of a supplementary food for vulnerable groups].

A supplementary meal based on locally produced (North West, Argentina) cereals and legumes was developed. The meal composition was as follows:extruded corn/soy (70:30) enzimatically modified; sugar; soy protein concentrate and additives. This preparation was characterized as an intermediate moisture content meal. Its adequate water content (35%) provides some plastic behaviour. Due to its low water activity (0.823) the formulation does not demand special requirements either for packing or storage. This meal provides high caloric density (3.06 Kcal/g) with a proper calories:nitrogen ratio (234). The protein quality was evaluated through the Relative Net Protein Ratio Method (R.N.P.R.) giving a result of 83.5%. The evaluation of its nutritional properties, as well as its stability and acceptability features, suggest that this product is appropriate for being included in food assistance programs.

Dietary Supplements↗

PubMed1997

[Comprehensive study of the geometry, surface area, membrane reserve potential, and osmoregulation of blood leukocytes].

Comprehensive method for examining the morphology and function of leukocytes is based on the comparison of the size and count of cells before and after incubation of different duration in media with low osmolarity. The method helps assess the leukocyte geometry, the reserve potential of the cytoplasmatic and nuclear membranes, the regulatory features and osmotic stability of cells.

Cell Membrane↗

PubMed2005

Structural features of thermozymes.

Enzymes synthesized by thermophiles and hyperthermophiles are known as thermozymes. These enzymes are typically thermostable, or resistant to irreversible inactivation at high temperatures, and thermophilic, i.e. optimally active at elevated temperatures between 60 and 125 degrees C. Enzyme thermostability encompasses thermodynamic stability and kinetic stability. Thermodynamic stability is defined by the enzyme's free energy of stabilization (deltaG(stab)) and by its melting temperature (Tm). An enzyme's kinetic stability is often expressed as its halflife (t1/2) at defined temperature. DeltaG(stab) of thermophilic proteins is 5-20 kcal/mol higher than that of mesophilic proteins. The thermostability mechanisms for thermozymes are varied and depend on the enzyme; nevertheless, some common features can be identified as contributing to stability. These features include more interactions (i.e. hydrogen bonds, electrostatic interactions, hydrophobic interactions, disulfide bonds, metal binding) than in less stable enzymes and superior conformational structure (i.e. more rigid, higher packing efficiency, reduced entropy of unfolding, conformational strain release and stability of alpha-helix). Understanding of the stabilizing features will greatly facilitate reengineering of some of the mesozymes to more stable thermozymes.

Archaea↗

PubMed2001

[The application of external knee stabilizers - Influence on mechanical stabilization and physical performance].

The aim of the study was, to assess the influence of a knee brace on the development of anterior instability after anterior cruciate ligament rupture and to test aptitude for physical strain. 46 subjects with arthroscopically proven anterior cruciate ligament rupture were divided equally in a randomised order into two groups. Both groups carried out a standardized physical therapy program, while one group (0) received additional stabilization by means of a functional knee brace (SofTec, Bauerfeind). In addition, important features of the brace (stabilization capacity, safety perception and physical performance) were tested and compared to the non-braced contralateral leg among 23 healthy physical education students by means of a standardized scaled questionnaire (observational study). 0 showed lower (p < 0.05) development of the anterior instability by 46 % and lower (p < 0.05) reduction in circumference of the femur muscles by 25 %. Increasing the time interval between accident and beginning of the brace treatment, increased the difference of the therapeutical effect of the brace. In the observational study, the brace received a better evaluation regarding all test parameters. The reduction of developing anterior instability by means of a brace should facilitate - apart from an individual operation-time-arrangement - especially a conservative approach within the framework of anterior instability and physical activity. Aside from the improvement of the mechanical stabilization, indications for suitability in strain situations could be detected for the tested brace.

Adult↗

PubMed2005

Anomalous size dependence in the melting temperatures of free sodium clusters: an explanation for the calorimetry experiments.

The meltinglike transition in unsupported Na(N) clusters (N = 55, 92, 147, 181, 189, 215, 249, 271, 281 and 299) is studied by first-principles isokinetic molecular dynamics simulations. The irregular size dependence of the melting temperatures Tm observed in the calorimetry experiments of Schmidt et al. [Nature (London) 393, 238 (1998)] is quantitatively reproduced. We demonstrate that structural effects alone can explain all broad features of experimental observations. Specifically, maxima in Tm(N) correlate with high surface stability and with structural features such as a high compactness degree.

Journal Article↗

PubMed2003

YADCLAN: yet another digitally-controlled linear artificial neuron.

This paper updates the author's 1999 RMBS presentation on digitally controlled linear artificial neuron design. Each neuron is based on a standard operational amplifier having excitatory and inhibitory inputs, variable gain, an amplified linear analog output and an adjustable threshold comparator for digital output. This design employs a 1-wire serial network of digitally controlled potentiometers and resistors whose resistance values are set and read back under microprocessor supervision. This system embodies several unique and useful features, including: enhanced neuronal stability, dynamic reconfigurability and network extensibility. This artificial neuronal is being employed for feature extraction and pattern recognition in an advanced robotic application.

Amplifiers, Electronic↗

PubMed2005

On the stability of the organic dication of the bisquaternary ammonium salt decamethoxinum under liquid secondary ion mass spectrometry.

In the course of a liquid secondary ion mass spectrometric (SIMS) investigation on a bisquaternary ammonium antimicrobial agent, decamethoxinum, unusual pathways of fragmentation of the organic dication M2+ of this bisquaternary salt, with preservation of the doubly charged state of the fragments, were observed. To reveal the structural and electronic parameters of decamethoxinum, which are responsible for the stabilization of its organic dication in the gas phase, a comprehensive SIMS study using metastable decay, collision-induced dissociation and kinetic energy release techniques complemented by ab initio quantum chemical calculations was performed. Pathways of fragmentation of two main precursors originating from decamethoxinum-organic dication M2+ and its cluster with a Cl- counterion [M.Cl]+-and a number of their primary fragments were established and systematized. Differences in the pathways of fragmentation of M2+ and [M.Cl]+ were revealed: the main directions of [M.Cl]+ decay involve dequaternization similar to thermal degradation of this compound, while in M2+ fragmentation via loss of one and two terminal radicals with preservation of the doubly charged state of the fragments dominates over charge separation processes. It was shown that pairing of the dication with a Cl- anion does not preserve the complex from fragmentation via separation of two positively charged centers or neutralization (dequaternization) of one such center. At the same time the low abundance of M2+ in the SIMS spectra is to a larger extent controlled by a probability of M2+ association with an anion than by the decay of the dication per se. Quantum chemical calculations of the structural and electronic parameters of the decamethoxinum dication have revealed at least three features which can provide stabilization of the doubly charged state. Firstly, in the most energetically favorable stretch conformation the distance between the quaternary nitrogens (rN1-N2=1.39 nm) is relatively large. Secondly, an intramolecular solvation of quaternary groups by carbonyl oxygens of the adjacent groups of the dication occurs, which contribute to structural stabilization. Thirdly, an important feature of the electronic structure of the dication is the presence of a partial negative charge on the nitrogen atoms and smearing of a positive charge mainly over the hydrogens of alkyl groups attached to the quaternary nitrogens, which reduces the net repulsion between the quaternary groups. The possible influence of charge smearing on the kinetic energy released on the dication fragmentation is discussed.

Anti-Infective Agents↗